Oronasal mask



Aug- 14, 1962 R. s. BRUMFIELD ETAL 3,049,121

ORONASAL MASK Filed Jan. 20, 1959 nui S .d R .K d a Wmwwm m 1w WMJ. A n akr .hand .wmh REF@ 3,049,121 Patented Aug. 14, 1962 fir 3,049,121 ORONASAL MASK Richard S. Brumfield, Edgewood, Ella Bickley Dwaayer, Magnolia, Frank shanty, Baltimore, and Charles J. Shoemaker, Towson, Md., assignors to the United States of America as represented by the Secretary of the Army Filed Jan. 20, 1959, Ser. No. 788,025 Claims. (Cl. 128--146) (Granted under Title 35, U.S. Code (1952), sec. 266) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment to us of any royalty thereon.

This invention relates to a disposable oronasal mask which is designed to afford protection to the wearer against toxic or other harmful aerosols and low concentrations of toxic vapors, as well as against objectionable odors. Conversely, it affords protection to others against transmission of respiratory infections from the wearer. It is characterized by very high efficiency, low cost and compactness in storage.

In the drawing, FIGURE l is a perspective View showing the mask in use on a wearer, FIGURE 2 is a plan view of a mask attached to a backing sheet for storage, and FIGURE 3 is a Section on the line 3 3, FIGURE 2.

The mask includes a substantially fiat filter 1, which is formed of a pleated sheet of lter material and is stitched at 3 about its periphery to hold the pleats flat and to prevent fraying `at the edges. A continuous boundary strip 5 of ordinary surgical adhesive tape or similar material surrounds the filter 1. The pressure sensitive tacky surface of the tape is adhered to the outer surface of filter 1 about its entire periphery, overlapping the stitched seam 3 at 7, forming a gas tight seal. The tape extends beyond the periphery of filter l so that it may be adhered to the face of the wearer or to other supports, as will be explained later in this specification.

A strippable sheet, preferably formed of two overlapping sections 9, 11, is adhered to the adhesive strip 5 and covers the inner surface of the filter 1. This sheet is formed of material which is impervious to air, vapors and aerosols, for example, cellophane or other sheet plastic. It serves to prevent contamination of the inner surface of the lter 1 prior to use as well as to protect the adhesive boundary strip 5.

The outer periphery of the boundary strip 5 is such as to enable the mask to be fitted to the face without wrinkling and with a minimum of folding. Preferably, it takes the form of an irregular pentagon. In more detail it includes lower edge 13, which fits under the chin of the wearer, two substantially straight edges, 15, 17 which are at least approximately at right angles to edge 13 and which are adapted to extend up the cheeks, and two converging upper edges 19, 21 which are adapted to extend inwardly across the cheek bones, as shown in FIGURE l. Edges 19 and 21 are joined by a generally arcuate notch 23 which, as shown in FIGURE 2, is ofi set from the axis of the mask, leaving two points 25, 27 of unequal height. Edges 13, 15, 17, 19 and 21 are joined to each other 'by arcs of relatively large radius. The mask is adhered to the face in approximately the position shown in FIGURE l. Point 27 is folded over the nose of the wearer and over point 25. The provision of arcuate notch 23 and the unequal points 25, 27 is a major factor in making it possible for a fiat mask to be properly tted to the contours of the face. The provision of `arcuate corners joining the straight sides is also important from that standpoint. Preferably the radius of each of these arcs is about 11/2 inches. The shape that we have adopted makes it possible to package the mask in an unfolded flat state, making for compact storage. Making the mask fiat also decreases the lcost of manufacture as compared to that for one having a conical or irregular shape. We thus secure at the same time a good t for the contours of the face, compactness for storage and cheapness of manufacture.

A sheet of filter material is die-cut following the sealing of a starch-sized cotton scrim to each side of the filter material by an iron-on process carried out While the scrim is damp. The die-'cut filter is then pleated using a stand- Iard three-to-one pleat. Alternatively, the material may be first pleated then cut to the shape of filter 1. The filter then is stitched about its periphery at 3 using a standard sewing machine. This serves to fiatten the pleats at the periphery of the filter yet does not reduce filtering area significantly. Adhesive tape is then die-cut to the shape shown in FIGURE 2. In both of the cutting steps a simple steel rule die may be employed. The filter material is then adhered to the adhesive boundary strip, so as to occupy the desired position. Finally, the backing sheet, 9, 12 is adhered to the tape, giving the article shown in FIGURE 2.

Immediately before use the backing sheet is removed and the mask is carefully fitted to the lface in the position shown in FIGURE l. As previously mentioned, the long point 27 is folded over the nose and the point 25.

Similarly, a plurality of masks of the ytype shown may be fixed to suitable windows to provide enhanced filtering area incertain applications, or a larger filter of the same basic structure but of suitable size and shape may be fastened over a Window or similar opening.

The filter material may be either one of two classes and it will be understood of course that other suitable material may be used. One class that we have used successfully is the aerosol filter material composed of organic fibers and either fine glass fibers or fine asbestos fibers which is employed to provide protection against dust, smoke, mist and other aerosols but does not provide protection against gases and vapors.

Suitable filter material of this class is described in the U.S. Military Specification, MIL-F13785 A, Nov. 12, 1954, amended August 3, 1956. We have successfully used Types 5 and 8 as defined in that specification.

yType 5 is a material having a very low resistance to air flow and is particularly desirable when the mask is to be used as a surgical mask or for protection against nontoxic dusts. The Type 8 is a heavier material which may be used to provide protection against toxic aerosols. A typical fiber formulation of the Type 5 material is as follows:

Fiber: Percent by weight Viscose rayon (1.5 denier, 1/s in. cut) 60.0 Cotton flock 30.0 Hemp 5.0 Blue Bolivian asbestos 5.0

Fiber: Percent by weight Viscose rayon flock 35 Cotton iiock 60 'Cocoa fiber 2 Blue African asbestos 3 A typical formulation of the Type 8 material is:

Fiber: Percent by weight Causticized viscose rayon (1.5 denier, M3 in.

cut) 46.3 Causticized woodpulp 23.9 Causticized rope fibers (hemp) 9-.8 Glass fibers-0.4 to .75 micron diam 20.0

T he physicalproperties of the materials are set out in detail in the -Military Specication referred to above.

The `other class is the gas-aerosol lter material which employs the above ingredients-and also includes 25% or more of activated charcoal in a nely divided condition. Such materials provide protection against aerosols and also against high-molecular-weight organic gases and vapors. We have successfully used the Type 5 material mentioned above impregnated with about 5 g per 100 sq. c-m. of activated carbon having particle sizes in the approximate range -of 5 0 to '20() mesh.

While we have described one embodiment of our invention in considerable detail, it will be obvious that various modifications are possible.V We therefore wish our invention to be limited solely by the scope of the appended`claims.

lWe claim:

`l. An oronasal mask comprising a flat sheet of pleated filter material, stitching about the outer periphery of said pleated filter material-for maintaining said'pleats in an overlapping relationship, adhesive tape provided witha central opening adhesively secured to said pleated lter material at its outer periphery and having a remaining portion clear of said'lter material so that it may be adhesively secured to theface of the wearer.

2. A mask as defined in claim 1 and further comprising a strippable sheet adhered to said-adhesive tape and covering' one surface of saidlter.

Cil

4 3. A mask as dened in claim 2 in which said strippable sheet comprises two separate, overlapping portions.

4. A mask as dened in claim 1 wherein said filter material is a gas-aerosol filter material formed of fibrous material impregnated with activated charcoal.

5. An oronasal mask comprising a ilat sheet of pleated aerosol filter material and a continu'ousboundary stripV of adhesive tape extending about and overlappingrthe periphery of saidlter material and adhered to the surface thereof, said tape extending Ibeyond the periphery of said sheet of lter material, whereby it may be adhered to the face of the wearer, the peripheryv of said tape including a lower edge adapted to t under the chin of the wearer, two substantially parallel side edges `adapted to extend up the cheeks of the wearer, and'twoconverging upper edges adapted to extend inwardly acrossthe cheek bones of the wearer, said upper' edges lbeingjoined by a generally arcuate notch oiTset-from the axis of said mask leaving two points of unequal heightand-adapted to t yover the nose of the wearer, vsai-d sheet of lter material being of such size and shape'asto coverfthemouth and nostrils of the wearer.

References Cited inl'the le of this patent UNITED STATES PATENTS 

